A two-temperature kinetic model of SF6 plasma

Studying the influence of thermal departures from equilibrium in SF6 circui t-breakers, we develop a two-temperature kinetic model to calculate the com position. Such a kinetic approach has not been adopted until now for SF6 pl asma because of the complexity of chemical processes. Our model takes into account the collisional mechanisms responsible fat the creation and disappe arance of atoms and molecules through 19 species linked by 66 chemical reac tions. To solve the conservation equations, the model uses the direct rates of reactions, that mainly proceed from the literature, and reverse rates, that are computed by two-temperature micro-reversibility laws. Thus, we poi nt out the importance of the choice of the expression of Saha law, comparin g Potapov and van de Sanden formulations of this law. We then discuss the i mpact of thermal departures from equilibrium on plasma composition, on 'mea n path' of molecules before dissociation in the plasma, and on the reaction s that govern the disappearance of electrons.